An existing electric vehicle usually has two transmission shafts, and each transmission shaft drives a pair of wheels located at opposite sides of the vehicle. All transmission shafts are controlled by one drive motor arranged at the front or rear of the vehicle. According to the number and the positions of the transmission shafts driven by the drive motor, the electric vehicle can realize front-wheel drive, rear-wheel drive or four-wheel drive.
For a vehicle with larger carrying capacity, for example, a large or heavy passenger car or truck, its chassis generally includes more transmission shafts, for example, four shafts, six shafts or eight shafts. The driving structure of such a vehicle is complex, and it is very difficult to realize the corresponding eight-wheel drive, twelve-wheel drive or sixteen-wheel drive. Moreover, due to the limit of the existing electric energy storage technology of the electric vehicle, when considering the necessary power demand and endurance mileage, such vehicle generally adopts a fuel engine as a direct power source, instead of being driven by the drive motor just like the electric vehicle.